Soundproofing certificate

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The noise protection certificate is a scientific report, usually created as part of a building permit procedure, which is intended to prove that the legal requirements for noise protection for a building project are complied with. The essential requirements are limit values ​​for the minimum noise protection against external noise (street noise, neighboring use, other noise emissions), whereby a distinction must be made between airborne noise and impact noise . The noise within a usage unit, for example in an open-plan office, is rarely part of the application process, but the sound absorption requirements of components are important in the context of occupational health and safety .

Contents of the noise protection certificate

The building regulations of the federal states require proof of sound insulation in the building permit procedure. The building supervision waives the proof for smaller projects. In most cases, proof is required that the arranged external components provide adequate protection against external noise and that the construction method ensures that the footfall sound does not disturb other usage units.

Proof of protection against external noise

Table 8 of DIN 4109 is used for the requirements for airborne sound insulation. This specifies minimum values ​​for the "resulting sound reduction index", sorted according to noise level ranges . An exterior wall for a residential building must achieve a sound insulation level of 40 dB in noise level range IV (including the reduction through e.g. windows), the higher the better.

Determination of the relevant external noise level DIN 4109

The classification of the relevant external noise is based on the traffic load, meaning road traffic. Surcharges must be added depending on the special conditions. If an intersection equipped with traffic lights is less than 100 m away from the immission point, 3 dB must be added, for rail traffic 3 dB. The relevant external noise level can also be determined by measuring according to DIN 45642. Special development allows a reduction without proof, in the case of block development by 10 dB. In some municipalities, mostly metropolitan areas, fixed guidelines are made for roads, which must then be observed.

Calculation example for the protection of external noise

  1. Given: lounge of an apartment in noise level range IV: 40 dB
  2. Room height: 2.60 m, room depth: 5 m. The division (2.6 / 5) gives 0.52. The correction value from Table 9, DIN 4109 is −2 dB
  3. The requirement for the resulting airborne sound insulation: erf R ' w, res = 40 - 2 = 38 dB
  4. A wall made of 30 cm light vertical perforated brick, gross density 700 kg / m³ is planned. Added to this are the values ​​for interior and exterior plaster, and when converted to m², the area-related mass is m '= 259 kg / m². The table in supplement 1 of DIN 4109 gives a sound reduction index of R ' w, W = 47 dB for single-leaf, rigid walls . The wall structure meets the requirements. Windows with R ' w, F = 32 dB are provided.

Dimensioning the impact sound insulation

With proof of impact sound insulation, the existing impact sound properties of the components must be smaller (= or equal to) than those prescribed by law (existing L ' n, w <= erf L' n, w ). Table 3 of DIN 4109 provides the specifications in the column "erf L ' n, w " in decibels (dB). For example, a storey ceiling for a generally usable storage room must meet at least 53 dB, this applies to airborne noise and impact noise. If the building project has fewer than three residential units, the requirement for airborne sound is reduced to 52 dB, for impact sound it increases to 63 dB, in the verification process it is reduced (see the formula in the paragraph)!

Proof of impact sound insulation using an example

Consider a semi-detached house with a concrete floor that separates a living room from a dry floor.

  1. The requirement: erf L ' n, w <= 63 dB - 2 dB (safety margin) = 61 dB
  2. The concrete ceiling with a thickness of 14 cm results in a bulk density of 320 kg / m² and 77 dB. The raw density of the concrete results from DIN 1055. The requirement is not met in this way.
  3. A screed is to be arranged that contains insulation panels made of mineral wool or polystyrene between the ceiling and the screed. A screed with a mass per unit area of ​​more than 70 kg / m² achieves an assessed impact sound reduction of 23 dB.
  4. Calculation: impact sound ceiling - impact sound reduction screed = 77 dB - 23 dB = 54 dB.
  5. Proof: exist L ' n, w <= erf L' n, w = 54 dB <= 61 dB. Evidence is provided.

The calculation of the sound absorption as "internal" proof of sound insulation

The calculation of the sound absorption should ensure ergonomically compatible working conditions, for example in an open-plan office. The noise energy generated in the office (telephone, discussions, etc.) should be reduced by suitable measures. Unfavorable room conditions can significantly reduce productivity and even lead to health problems. The procedure is regulated in DIN 18041 and applies to small to medium-sized rooms (up to 4000 m²). The sound absorption values ​​of the most common components are also given in the appendix. A wide variety of information can be found in the literature regarding the sound absorption values ​​for furnishings and people. This can reduce planning security.

Evidence of sound insulation using an example

An office with two workplaces is to be examined. The room has a simple, rectangular shape, one long side has a window wall, the other long wall is made of lightweight construction. The front sides are made of solid construction and drywall. The ceiling is suspended and the floor is covered with parquet. The dimensions are: 5 m * 8 m * 3 m (width, length, height), the volume is therefore 120 m³. The steps in detail:

  1. The room geometry is to be recorded. This includes the areas of the floor, ceiling and walls individually recorded according to their surface material. A floor that is half covered with parquet and the other half with carpet is to be covered here with two surfaces.
  2. The required degree of absorption can be calculated using the formula: A (in m²) = 0.163 * V / T. V means the volume and T the reverberation time, here 0.55 sec. In the office (and most common rooms) the reverberation time should be between 0.5 and 0.6 sec. The calculation results in a required degree of absorption of 35.6 m².
  3. The existing degree of absorption must be determined. To do this, the surfaces of the walls, ceiling and floor must be multiplied by the values ​​given in the appendix to DIN 18041 for the respective materials. The decisive factor is the value for 500 Hz. The values ​​for the furniture and most of the people present are to be set with care. The sample calculation shows an absorption level of a good 20 m². By comparing the required degree of absorption of a good 36 m², the result is an absorption deficit of 16 m², which must be retrofitted accordingly.
  4. The measures to be taken can be calculated technically and economically by optimizing and retrofitting sound absorbers such as curtains, carpets, movable soundproof walls, ceiling sails, acoustic pictures, etc. For example, an acoustic image (with internal insulation mat) in size DIN-A-0 (1 m²) would result in a sound absorption of almost one m².

The procedure is simple, but special room geometries are not provided for in the standard. A lounge with concave walls loses a disproportionately large amount of room quality due to the "sound migration", as the noise generated here is amplified and unpleasant.

See also

Individual evidence

  1. For example the "Ordinance on building templates and building inspectorate notifications" in Bavaria, where in §12 you can read: "The calculations must prove the heat, noise and vibration protection required by building regulations."
  2. DIN 4109, table 8
  3. Calculation example from Klaus-Jürgen Schneider (editor): Construction tables for architects with calculation instructions and examples, 16th edition, 2004, Munich, ISBN 3-8041-4181-1 , p.10.52
  4. With cement screeds of 0.22 kN / m² / cm, this is achieved from a thickness of 4 cm. For structural reasons, a screed on insulation boards should be at least 5 cm
  5. Calculation example from Klaus-Jürgen Schneider (editor): Construction tables for architects with calculation instructions and examples, 16th edition, 2004, Munich, ISBN 3-8041-4181-1 , p.10.64
  6. Calculation: Author according to DIN 18041